Light emitting devices, such as lasers, have been used as a sensor component to gather information in various applications. For example, time of flight measurement apparatuses, such as laser scanners and light detection and ranging apparatuses (hereinafter referred to as “LIDAR”), have been used for many applications. Examples of such applications include terrain mapping, bathymetry, seismology, detecting faults, biomass measurement, wind speed measurement, Differential Absorption LIDAR (DIAL), temperature calculation, traffic speed measurement, object identification, high definition surveying, close range photogrammetry, atmospheric composition, meteorology, distance measurement, as well as many other applications.
LIDAR has been increasingly used for surveying and topographical mapping of geographical areas, for example, using downward-looking LIDAR instruments mounted on aerial platforms, such as aircraft or satellites. Such LIDAR instruments are used to determine distances to a surface, such as a surface of an object or a terrain surface, using pulses of light. The range to the surface is determined by measuring the time delay between transmission of a pulse of light and detection of a corresponding reflection signal. In such systems, speed of light is used as a known constant for calculating the distance using the time of light travel.
The location of a surface can be calculated based on: (1) the angle with respect to the system at which the pulse of light is transmitted, (2) the orientation of the system with respect to the earth and (3) the current location of the system. As the measurements progress, data from rapid laser firings, often numbering in the millions, can be captured and additional data models describing the reflecting surface can be recorded.
There remains a need, however, for improved range finding apparatuses, such as LIDAR apparatuses for use on aerial platforms, having improved performance characteristics and improved safety characteristics.